let str = 'Damn'
let num = 123
let flag = false
let un = undefined
let nu = null

let obj = {}
let arr = []
let fn = function (){}

console.log(str instanceof String);  // false
console.log(num instanceof Number);  // false
console.log(flag instanceof Boolean);// false

console.log(obj instanceof Object);  // true
console.log(arr instanceof Array);   // true
console.log(fn instanceof Function); // true